1/* SPDX-License-Identifier: GPL-2.0-only */
2
3#ifndef LINUX_RESUME_USER_MODE_H
4#define LINUX_RESUME_USER_MODE_H
5
6#include <linux/sched.h>
7#include <linux/task_work.h>
8#include <linux/memcontrol.h>
9#include <linux/blk-cgroup.h>
10
11/**
12 * set_notify_resume - cause resume_user_mode_work() to be called
13 * @task: task that will call resume_user_mode_work()
14 *
15 * Calling this arranges that @task will call resume_user_mode_work()
16 * before returning to user mode. If it's already running in user mode,
17 * it will enter the kernel and call resume_user_mode_work() soon.
18 * If it's blocked, it will not be woken.
19 */
20static inline void set_notify_resume(struct task_struct *task)
21{
22 if (!test_and_set_tsk_thread_flag(tsk: task, TIF_NOTIFY_RESUME))
23 kick_process(tsk: task);
24}
25
26
27/**
28 * resume_user_mode_work - Perform work before returning to user mode
29 * @regs: user-mode registers of @current task
30 *
31 * This is called when %TIF_NOTIFY_RESUME has been set. Now we are
32 * about to return to user mode, and the user state in @regs can be
33 * inspected or adjusted. The caller in arch code has cleared
34 * %TIF_NOTIFY_RESUME before the call. If the flag gets set again
35 * asynchronously, this will be called again before we return to
36 * user mode.
37 *
38 * Called without locks.
39 */
40static inline void resume_user_mode_work(struct pt_regs *regs)
41{
42 clear_thread_flag(TIF_NOTIFY_RESUME);
43 /*
44 * This barrier pairs with task_work_add()->set_notify_resume() after
45 * hlist_add_head(task->task_works);
46 */
47 smp_mb__after_atomic();
48 if (unlikely(task_work_pending(current)))
49 task_work_run();
50
51#ifdef CONFIG_KEYS_REQUEST_CACHE
52 if (unlikely(current->cached_requested_key)) {
53 key_put(current->cached_requested_key);
54 current->cached_requested_key = NULL;
55 }
56#endif
57
58 mem_cgroup_handle_over_high(GFP_KERNEL);
59 blkcg_maybe_throttle_current();
60
61 rseq_handle_notify_resume(NULL, regs);
62}
63
64#endif /* LINUX_RESUME_USER_MODE_H */
65

source code of linux/include/linux/resume_user_mode.h